Why are bogs important?
Peatlands, or bogs, are a distinct feature of the Irish landscape and are at the core of Ireland’s rich cultural heritage, traditions, and way of life. Peatlands are a type of wetland that form in areas that are waterlogged year-round and cover an estimated 3% of the Earth’s surface. Proportionately, Ireland has the second highest coverage of peat in the Europe at 17%, after Finland2. In Ireland there are two distinct types of peat bogs: raised bogs and blanket bogs. Blanket bogs are the most common on the Iveragh Peninsula.
The first survey of the bogs of Kerry and the barony of Iveragh was undertaken by Alexander Nimmo in 1811, under the Irish Bogs Commission. The commission was set up to explore the potential to reclaim and utilise Irish bogs for agriculture. These surveys were the first time that detailed maps of large areas of Ireland were produced.
Raised Bogs
Raised bogs are flattened domes of peat that are particularly common in the midlands of Ireland but also scattered across some areas of Kerry. While there are no raised bogs on the Iveragh Peninsula, there is one raised bog, Sheheree Bog, in the Killarney area, and there are more further north. Raised bogs can reach depths of up to 12m, growing at a rate of roughly 1mm per year and are found in altitudes below 130m where rainfall is between 800 and 900mm annually.
Sphagnum Moss is adapted to living in bogs. It adds colour, helps bogs to grow, and has many health uses.
Raised bogs began to form around 10,000 years ago, following the last glacial period. As the ice sheets retreated, they left behind a heavily disturbed and hummocky landscape with large ridges of glacial deposits and many potholes and depressions. Vast quantities of meltwater drained from the ice sheets and was trapped within these depressions, forming thousands of lakes across Ireland. Plants such as reeds grew along the fringes of these lakes. When these plants died and fell into the shallow lakes, they didn’t completely decompose in the wet, oxygen depleted conditions that were prevalent in these lakes. Gradually, undecomposed plant material built up to form a layer of peat below the water level. The peat layers thickened and expanded, and the lakes contracted until a raised bog developed above the water level. As the lake filled with peat, access to the nutrient rich groundwater was cut off. This meant that the only water supply came from the acidic and nutrient poor rainwater. This favoured the growth of plants adapted to acidic soil, such as Sphagnum mosses. Sphagnum exists as a hummocky and hollowed living carpet floating on the underlying peat material, which can be up to 90% water.
Blanket Bogs
We are all familiar with the sight of blanket bogs in Kerry. They cover a large proportion of our landscape and are often covered by gorse, rushes, and small shrubs. Globally, blanket bog is rare, and Ireland is believed to possess around 8% of the worldwide total. Blanket bogs form in areas of high rainfall and low evaporation. The Iveragh Peninsula has mild winters, cool summers, and a very wet climate (mean average rainfall of 1557.4mm per year, as measured from the Valentia Observatory), making it the perfect environment for blanket bogs to form. Blanket bog is further categorised into Atlantic blanket bog and Mountain blanket bog, both of which can be found across Iveragh.
Blanket Bog along the Fermoyle Loop near Sneem.
Atlantic blanket bogs cover areas in the west of the country where rainfall is roughly 1,200mm per year at altitudes from sea level to about 200m. These lowland blanket bogs comprise less than 3% of the world’s peatlands and in Europe are restricted to Ireland, Britain, Norway and Iceland.
Mountain blanket bogs are found on relatively flat terrain in altitudes of over 200m. These bogs are fed by heavy rainfall with a vegetation characterised by low shrubs. Over 65% of the Iveragh Peninsula, including the Mcgillicuddy’s Reeks, is classed as uplands (land with altitudes of over 150m) and upland blanket bog is amongst the most frequently occurring habitat types across Iveragh.
The formation of blanket bogs is closely linked with human activity in Ireland and is the unintentional product of forest clearance. During the last glacial period, plant life could not withstand the harsh cold conditions and so retreated further south to warmer areas in Europe. As the ice sheets melted, plants gradually returned to Ireland, with tundra giving way to woodland. By around 4000BC, Ireland was densely forested across the lowlands and slightly more sparsely forested in upland areas. While Mesolithic people may have had some impact on these woodlands, it is during the Neolithic Age, with the advent of farming that land clearance really began to take a toll on the landscape. Neolithic farmers initially focused on upland areas, where forests were not as thick.
As people cleared forests, water-soluble minerals and nutrients began to leach from the top layers of the soil, which then became more acidic. These leached materials accumulated deep within the soil, forming an impermeable mineral layer, known as an iron pan, which restricted drainage. The soils above this layer became waterlogged, acidic, and depleted of nutrients. In these conditions, only species like heathers and rushes can survive and plant debris does not fully decay, but instead accumulates to form peat. Over thousands of years, this peat has built up to form blanket bogs, creating a rare and biodiverse habitat in the process. By the Bronze Age, farmers had been forced down to lower ground and bog spread further, swallowing up lingering trees and farmland.
Blanket bogs are now a ubiquitous feature of Iveragh; the squelchy hillsides and fields are encountered almost everywhere. The Inny Valley and the area around Portmagee have the most extensive peat soil formations. Knockroe Bog, located approximately 13km south east of Cahersiveen in the valley of the Owroe River, is a designated Natural Heritage area (https://www.npws.ie/protected-sites/nha/000366). This is an Atlantic blanket bog and is important for its diversity of habitat features including bog pools and as a representative of the near southern limit of blanket bogs in the Northern Hemisphere. While this is the only peatland with such a designation on the Iveragh Peninsula, Cummeragh River Bog (https://www.npws.ie/nature-reserves/kerry/cummeragh-river-bog-nature-reserve), located to 8km to the north-east of Waterville, is a state-owned Nature Reserve. Coad Bog, located between Caherdaniel and Castle Cove is an IPCC (Irish Peatland Conservation Council) reserve (http://www.ipcc.ie/discover-and-learn/ipccs-peatland-nature-reserves/coad-bog-visitor-map-and-guide/). This bog was donated to the IPCC in 2015 and is an important conservation site. Coad Bog hosts 13 different habitat types, covering an area of 4 hectares and over 200 species of wildlife have been recorded here. Located along the Ring of Kerry, Coad Bog is an ideal spot for those eager to explore Ireland’s unique blanket bogs.
Coad Bog near Castlecove is owned by the Irish Peatland Conservation Council and is a fine example of the biodiversity that bogs can support.
Importance
Bogs are among the most important habitats in the world and fulfil a diverse range of cultural and environmental functions. Irish bogs preserve archaeological evidence of early humans in Ireland including traces of prehistoric farming practices, artefacts and even bog bodies. In addition to this record of human history, bogs preserve an important record of post glacial climate and vegetation changes, as well as the remains of fauna that roamed the early post glacial landscape, such as the Great Irish Deer. In rural communities, peat has economic significance as a source of fuel and as grazing land for sheep and cattle. However, bogs have been heavily modified and degraded by hundreds of years of human activity and it is critical that we now protect these environments. The Irish Peat Conservation Council (IPCC) works to conserve peatland heritage across Ireland.
Bogs are extremely biodiverse, and as a result have been designated as priority habitats under the EU Habitats Directive due to their scarcity across Europe. The bogs of Iveragh contain rare combinations of species including animals such as Hares (Giorria), Frogs(Frog), Newts (Earc sléibhe) and Lizards(Laghairt choteann), as well as incredible numbers of invertebrates such as Butterflies(Féilecán), Dragonflies (Snáthaid mhór), Moths (leamhan), and Spiders(Damhán alla).
Common Frog - one of the many species that inhabit our bogs.
While at first glance bogs may appear flat, monotonous, and dull coloured, close inspection reveals the patchwork of pink, red, copper, and yellow mats of Sphagnum moss. Blanket bogs are dominated by species like Black bog rush (An Sifín), Purple moor-grass (Fionnán) and the particularly striking Bog Cotton (Ceannbhán). The bogs of Iveragh host remarkable carnivorous plants like Bladderworts (Lus borraigh beag), Butterworts (Bodán meascáin) and Sundews (Cailís Mhuire). In the spring and summer months, splashes of colour are sprinkled across the peatlands as wildflowers burst into bloom. Just some of these wildflowers include Orchids (Magairlín), Bog Asphodel (Sciollam na móna), and Tormentil (Néalfartach).
Bog Cotton is just one of the many unusual plants that thrive on our bogs.
Peatlands are not only beautiful and biodiverse habitats but perform a range of critical ecosystem services. In Ireland, peatlands are key in carbon sequestration and are estimated to store 1085 Mega tonnes of carbon. That’s about 53% of the total amount of carbon locked in Irish soils, even though they only cover 17% of the island. As plants grow, they remove carbon dioxide from the air through photosynthesis. When these plants die and break down to form peat, this carbon is retained and placed under long term storage for thousands of years. Intact peatlands are an extremely efficient global carbon sink, estimated to store twice as much carbon as all the world’s forests combined. However, once peatlands are damaged, this carbon, as well as other greenhouse gases such as methane, are released back into the atmosphere. Damage to peatlands results from afforestation, overcutting, overgrazing, drainage, and infrastructure. Preserving these incredible habitats is of the utmost importance not only to protect biodiversity but also to ensure that Ireland meets its climate change mitigation targets.
While the carbon storage potential of bogs has become more widely known, their capacity to perform a range of water services is less widely acknowledged. Bogs retain large quantities of water, acting as huge water reservoirs with the ability the regulate water supply. In times of intense rainfall, bogs can absorb and hold on to huge amounts of water. Sphagnum can absorb up to 20 times its own weight in water! Once conditions dry out, this water is slowly released. In this way, bogs can regulate stream flows and prevent flooding.
References
Montanarella, L., Jones, R., & Hiederer, R. (2006). The distribution of peatland in Europe. Mires and Peat, 1.
Xu, J., Morris, P. J., & Liu, J. (2018). PEATMAP: Refining estimates of global peatland distribution based on a meta-analysis. Catena, 134-140.
Kramm, N., Anderson, R.M., P’Rourke, E., Emmerson, M.C., O’Halloran, J., & Chisholm, N. (2010). Farming the Iveragh uplands: A tale of humans and nature. University College Cork.
Tomlinson, R.W. (2005). Soil carbon stocks and changes in the Republic of Ireland. Journal of environmental management, 76(1),77-93.
